The present invention relates to video tape recorders (VTR), and more particularly, to a system for changing the duration of playback time of a fixed length segment of recorded tape.
Television broadcasters normally receive prerecorded programs that are of a fixed length, thus leaving only a certain amount of time from a fixed time slot, of, e.g., 1/2 or 1 hour, for advertisements. If the broadcaster receives orders for advertisements that exceed in time the time remaining for advertisements, at least one advertisement must be rejected, which results in a loss of revenue. Further, television production companies find that when assembling a video tape recording during an editing step, a segment frequently must be added to a prerecorded tape, which segment is frequently too long or too short to fit into the time segment alloted to it. If the segment is too long, it is corrected by deleting from either the dropped-in segment or the prerecorded tape. If the segment is too short, it is difficult to correct. The result is a loss of artistic integrity of the work.
It is known to speed up or slow down a tape manually such as in the so-called "Moviola" technique. However, this technique is unsuitable for broadcast use since the tape speed is not known and the quality of reproduction is inadequate. For these reasons, this technique is used only for tape editing.
It is therefore desirable to have a system that prevents a loss of revenue to broadcasters and/or loss of artistic integrity of a program by enabling time changing (lengthening or shortening) of a prerecorded program. Further, it is desirable to carry out the time changing with a minimum of human error, and with a minimum of visible effects.